Hi Ruger-Redhawk,
I don't believe the XD comes in .45ACP yet. However if Glock releases the .45GAP for general use (non-proprietary....and I don't know if it is or isn't?!?) the XD could be chambered in .45GAP with no other modifications. I wouldn't be surprised to find out that a .45ACP version is already in the works. (Though with Springfield's other model .45's maybe not!)
Personally I like the XD and have a 4" chambered in .40S&W. But I also like the .45ACP and have a ParaOrdnance P-12. So I guess I have both covered

! Also currently looking at another 1911.....though I haven't exactly made up my mind about the manufacturer or length! Or for that matter blue or stainless. Maybe I'll have to get several

!
Dave